[PATCH] thunderbolt: property: fix a buffer overflow and a missing check

[PATCH] thunderbolt: property: fix a buffer overflow and a missing check

[Kangjie Lu]

First, no memory is allocated for "property->value.text"; the
following strcpy will lead to a buffer overflow.

Second, no check is enforced for the return value of kzalloc,
which may lead to NULL-pointer dereference.

The patch fixes the two issues.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
 drivers/thunderbolt/property.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/thunderbolt/property.c b/drivers/thunderbolt/property.c
index 841314deb446..d5b0cdb8f0b1 100644
--- a/drivers/thunderbolt/property.c
+++ b/drivers/thunderbolt/property.c
@@ -587,7 +587,12 @@ int tb_property_add_text(struct tb_property_dir *parent, const char *key,
 		return -ENOMEM;
 
 	property->length = size / 4;
-	property->value.data = kzalloc(size, GFP_KERNEL);
+	property->value.text = kzalloc(size, GFP_KERNEL);
+	if (!property->value.text) {
+		kfree(property);
+		return -ENOMEM;
+	}
+
 	strcpy(property->value.text, text);
 
 	list_add_tail(&property->list, &parent->properties);
-- 
2.17.1

Re: [PATCH] thunderbolt: property: fix a buffer overflow and a missing check

[Mika Westerberg]

On Sun, Mar 24, 2019 at 05:49:16PM -0500, Kangjie Lu wrote:
> First, no memory is allocated for "property->value.text"; the
> following strcpy will lead to a buffer overflow.

It is actually member of union so assigning via value.txt or value.data
is the same.

So no buffer overflow.

> Second, no check is enforced for the return value of kzalloc,
> which may lead to NULL-pointer dereference.

Yes, this is valid.

Can you fix the changelog accordingly and resend?

> 
> The patch fixes the two issues.
> 
> Signed-off-by: Kangjie Lu <kjlu@umn.edu>
> ---
>  drivers/thunderbolt/property.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/thunderbolt/property.c b/drivers/thunderbolt/property.c
> index 841314deb446..d5b0cdb8f0b1 100644
> --- a/drivers/thunderbolt/property.c
> +++ b/drivers/thunderbolt/property.c
> @@ -587,7 +587,12 @@ int tb_property_add_text(struct tb_property_dir *parent, const char *key,
>  		return -ENOMEM;
>  
>  	property->length = size / 4;
> -	property->value.data = kzalloc(size, GFP_KERNEL);
> +	property->value.text = kzalloc(size, GFP_KERNEL);
> +	if (!property->value.text) {
> +		kfree(property);
> +		return -ENOMEM;
> +	}
> +
>  	strcpy(property->value.text, text);
>  
>  	list_add_tail(&property->list, &parent->properties);
> -- 
> 2.17.1

Re: [PATCH] thunderbolt: property: fix a buffer overflow and a missing check

[Mukesh Ojha]

On 3/25/2019 4:19 AM, Kangjie Lu wrote:
> First, no memory is allocated for "property->value.text"; the
> following strcpy will lead to a buffer overflow.

Fix the commit text as there is no  overflow.

only the check and resource cleanp is the fix.

>
> Second, no check is enforced for the return value of kzalloc,
> which may lead to NULL-pointer dereference.
>
> The patch fixes the two issues.
>
> Signed-off-by: Kangjie Lu <kjlu@umn.edu
Otherwise looks good.

Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>

-Mukesh

> ---
>   drivers/thunderbolt/property.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thunderbolt/property.c b/drivers/thunderbolt/property.c
> index 841314deb446..d5b0cdb8f0b1 100644
> --- a/drivers/thunderbolt/property.c
> +++ b/drivers/thunderbolt/property.c
> @@ -587,7 +587,12 @@ int tb_property_add_text(struct tb_property_dir *parent, const char *key,
>   		return -ENOMEM;
>   
>   	property->length = size / 4;
> -	property->value.data = kzalloc(size, GFP_KERNEL);
> +	property->value.text = kzalloc(size, GFP_KERNEL);
> +	if (!property->value.text) {
> +		kfree(property);
> +		return -ENOMEM;
> +	}
> +
>   	strcpy(property->value.text, text);
>   
>   	list_add_tail(&property->list, &parent->properties);